下列哪项不是普萘洛尔治疗心绞痛的作用机制（）
A.抑制心肌收缩力
B.减慢心率
C.直接扩张冠脉
D.增加缺血区供血
E.心脏后负荷减少
参考答案：C
属于食管癌手术禁忌证的是（）
A.严重吞咽困难
B.声音嘶哑
C.肿瘤长度大于10cm
D.锁骨上淋巴结转移
E.恶病质
With his work completed,the business man stepped back to his seat,feeling pleased he was a man of action.
A．which
B．that
C．what
D．whether
